Techware Labs' charts are misleading. 

Single card vs crossfire 3D Mark 06, 11640:12514 yet the bar for crossfire is more than twice as long as non-crossfire.

Crysis 1680x1050 very high no AA. 19.01:22.045 yet the crossfire bar is more than twice as long as non-crossfire.

Similarly COD 4 maxed out, 78.074:90.134 yet the crossfire bar is more than twice as long as non-crossfire.

Yet for some reason the Devil May Cry bars are roughly the right relative size!
Techware Labs' charts are misleading. 

Single card vs crossfire 3D Mark 06, 11640:12514 yet the bar for crossfire is more than twice as long as non-crossfire.

Crysis 1680x1050 very high no AA. 19.01:22.045 yet the crossfire bar is more than twice as long as non-crossfire.

Similarly COD 4 maxed out, 78.074:90.134 yet the crossfire bar is more than twice as long as non-crossfire.

Yet for some reason the Devil May Cry bars are roughly the right relative size!